New ICI reduction schemes for OFDM system

Orthogonal frequency division multiplexing (OFDM) is sensitive to the carrier frequency offset (CFO). We introduce the peak interference-to-carrier ratio (PICR) to measure the resulting intercarrier interference (ICI). This paper shows that the PICR can be reduced by coding to select only those messages with low PICR as valid codewords. While explicit constructions of higher-rate, ICI-suppressing codes are rather difficult, we propose two new codes that map data onto three and four adjacent subcarriers. We also propose a new ICI reduction scheme, called tone reservation, that inserts optimized pilot tones in the data frame. Computing these pilot tones at the transmitter is a simple optimization technique.